energy harvesting from vibrations, air … harvesting from vibrations, air flow, ... wireless sensor...
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ENERGY HARVESTING FROM VIBRATIONS AIR FLOWVIBRATIONS, AIR FLOW,
& TEMPERATURE CHANGE
d ll l h dLindsay Miller, Alic Chen, Deepa MadanLee Weinstein, Peter So, Thomas Devloo,
D Eli b th R ill D Yi i ZhDr. Elizabeth Reilly, Dr. Yiping Zhu, Prof. Paul Wright, Prof. Jim Evans
System on a Chip
Wireless Sensor Energy Storage MEMS Sensor
Sensor
Micro‐device
Energy storage
Cable
Piezoelectric MEMS Cantilever
Microscale Magnet
Output Voltage
Magnetic Field
Cable
Piezoelectric MEMS Cantilever
Microscale Magnet
Output Voltage
Magnetic Field
Energy h ti
Radio
Energy Harvesting Radio
harvesting
Radio
Multi‐source energy harvesting
PIEZOELECTRIC THERMOELECTRICVIBRATIONS
TEMPERATURE DIFFERENCE
AIR FLOWAIR FLOW
Progress made in past 6 months:PIEZOELECTRIC THERMOELECTRIC
VIBRATIONS
TEMPERATURE DIFFERENCE
• Composite materials improved
D l d l bl f b i ti
• Prms = 1.1 nW/beam, micro device on ambient source
D l d t dif
TEMPERATURE DIFFERENCE
• Developed scalable fabrication process for meso‐scale devices
• P = 0.58 μW
• Developed process to modify frequency with printed mass
AIR FLOW
P 0.58 μW (ΔT = 10 K, 10‐couple device)
• Meso‐scale prototype developedMeso scale prototype developed
• Prms = 1.1 mW, optimal conditions
Multi‐source energy harvestingPIEZOELECTRIC
VIBRATIONS
AIR FLOWAIR FLOW
Piezoelectric operating principle DEFORMATION
(mechanical energy)VOLTAGE
(electrical energy)
3PIEZOELECTRIC MATERIAL CANTILEVER BEAM
12
3
+
V+
-
S. Roundy, PhD Thesis UC Berkeley 2003 Figure: Wikipedia, 2010
Where we left you 6 months ago:PIEZOELECTRIC Beam voltage output vs Frequency
VIBRATIONS
• MEMS harvester fabricated
put, mV
• Low resonance frequency achieved• Prms = 1 nW on shaker table• 1 beam tested on 1 ambient source ol
tage outp
• 1 beam tested on 1 ambient source• Printed capacitor on harvester die
Vo
Frequency, HzAIR FLOW
• Project was just starting
eque cy,
Progress: ambient vibration harvesting 2 /Hz
)
Ambient vibration source: compressor
2 /Hz
or A
2
ACCELERATION (MEASURED)
Density
(V2
Spectral D
BEAM OUTPUT (MEASURED)
TRANSFER FUNCTION (CALCULATED)
Power S
BEAM OUTPUT (CALCULATED)
BEAM OUTPUT (MEASURED)
T t d 9 b 7 bi t li bl d l
Frequency (Hz)
• Tested 9 beams on 7 ambient sources – reliably produce low power• Almost finished with model – measured accel. input predicted beam output
Progress: print mass modify frequency
Successfully printed on 6 released beams with no “casualties”
ω2 = k/mω k/m
2.5 mm 1.5 mm
1.5 mm 1.5 mm
Progress: print mass modify frequency
Beam power output vs frequency
Shift in frequency with addition of printed mass
177.9 Hz BEFOREBeam power output vs frequency
Beam signals add in series!
192.8 Hz
(nW
rms)
172.9 Hz
Beam signals add in series!AFTER
r outpu
t (
Frequency (Hz)0.1 Hz resolution> 20 Hz shift
MS Po
we
Series, theoretical
Series, measured
R
Right, measured
Left, measured
Frequency (Hz)
Progress: air flow harvester designTop View
Back View
Cylindrical Obstacle
Fin
Stand
Progress: air flow harvester performance
Power output > 1 mWi l di iat optimal conditions
For results shown:Fin: 7.5 cm wide x 7 cm longgFin material: balsa woodCylinder Diameter: 2.5 cmOptimum Load R: 194 kOhm
Multi‐source energy harvestingPIEZOELECTRIC THERMOELECTRIC
VIBRATIONS
AIR FLOWAIR FLOW
Multi‐source energy harvestingTHERMOELECTRIC
Thermoelectric (TE) Operating PrinciplesThermoelectric (TE) Energy Harvesting
Cold SideSubstrateHeat Sink
MetalInterconnects
N Type
N P
–– ++ΔT
Hot SideN‐Type
SemiconductorP‐TypeSemiconductor
Resistive LoadCurrent + –
Heat Source
Resistive Load
Sources of Waste Heat
Location Source Temp. Gradient
Residential Boilers, Dryers, Freezers, Oven 10‐30K Aluminum Smelter Boiler
Factories Exhaust pipes, Boilers, Condensers 10‐80K
Vehicles Engine, Exhaust pipes 60K 100Kg , p p >100K
Airplanes Cabin to External 10‐50K Dryer
Thermoelectric DesignTE Power Output Optimization
Optimal Range
Bulk elementsThin film elements
d l ff b •Diced elements from ingots•1mm height min.
• Labor intensiveM l i k & l
•Microfabrication processes•60μm max. height
•Materials intensiveMi l I
Dispenser Printing•Optimal Feature Sizes (100‐500μm) •Manual pick & placeMicropelt, Inc
Ferrotec, Inc.
( μ )•High throughput manufacturing
Where we left you 6 months ago:
THERMOELECTRICepoxyk THERMOELECTRIC
• Meso‐scale prototype
p yresin mix ink
fabricated using dispenser printing techniqueadd active
particles• Printable
semiconductor/epoxy thermoelectric materials
p
synthesized25 mm
1mm D, 1.5mm H
25 mm
Progress: innovative design of TE harvesterSubstrate
A t ti f 1 5 t 2
Metal
• Aspect ratios from 1.5 to 2• Commercially available• Labor intensive assembly
N‐TypeSemiconductorP‐Type
MetalInterconnects
P TypeSemiconductor
Metal Interconnects
N‐type Semiconductor
• High aspect ratio pillarsInterconnects
P type
• High density arrays• 900+ couples for D = 1cm
• Takes advantage of printing
18
P‐type SemiconductorFlexible
Substrateprocess
Progress: new design is easily scalableg g y1. Print Electrodes
2. Print N‐type Semiconductor
3. Print P‐type Semiconductor3. Print P type Semiconductor
4. Heat/Cure
• 3‐layer printing process l l h ll bl• Element lengths are controllable
• Printing process is scalable to larger prod ction processes (i e screenproduction processes (i.e. screen printing, flexography) 19
Progress: performance of TE prototypeThermoelectric Materials Flexible TE Devices
2.2 μW0.58 μW
•10 Couple Device•ΔT = 10 Kelvin• Losses from
Bi2Te3 Composites
Losses from contact resistance
2 3 p
Flexible Polyimide Substrate
Sb2Te3 Composites
Snyder et al (2008)
Printed TEMaterialsLeg Dim.: 5 mm Length, 500 µm width, 200 µm thick
Progress summaryPIEZOELECTRIC THERMOELECTRIC
VIBRATIONS
• Prms = 1.1 nW/beam, TEMPERATURE DIFFERENCE
• Synthesized efficient, printable composite TE materials (ZT ~ 0.4 )
Prms 1.1 nW/beam, micro device on ambient source
• Modified frequency by 20 Hz with
TEMPERATURE DIFFERENCE
• Developed scalable fabrication process for meso‐scale devices
• P 0 58 μW
printed mass • Beam signals add when in series
AIR FLOW• P = 0.58 μW (ΔT = 10 K, 10‐couple device)
• Meso‐scale prototype designed, p yp gbuilt, & characterized in duct
• Prms = 1.1 mW, optimal conditions
Thank you! Any questions?
CylindricalCylindricalCylindricalTHERMOELECTRIC
Cylindrical ObstacleCylindrical Obstacle
FinFin
Cylindrical Obstacle
Fin
AIR FLOW
StandStandStand
AIR FLOW
VIBRATION
1.3 cm
Acknowledgements: California Energy Commission, Siemens, CITRIS, Berkeley Manufacturing Institute, Berkeley Wireless Research Center